Energy is required for all living creatures to grow and reproduce, maintain their structures, and respond to their surroundings. Metabolism is a series of life-sustaining chemical processes that allow organisms to convert chemical energy held in molecules into energy for cellular functions. We already know that the source of energy is the food consumed by us. But how does the cell know, how to produce energy, when to use oxygen, how to use glucose, how many enzymes to produce? The DNA commands every single action in the living system.

The flow of energy and information within the living system is highly specific and organised machinery. Even the ability of formation of a multicellular foetus from a single-celled zygote is decided and controlled by the flow of energy and information. The ability to produce a whole organism from a single cell is referred to as totipotency and is a unique ability of a few cells. Read further to learn more about the flow of energy and information and totipotency.

Thermodynamics

The quantitative study of energy transductions that occur in or between living creatures, structures, and cells and the nature and function of the chemical processes behind these transductions is known as thermodynamics in biology.

Metabolism is a series of life-sustaining chemical processes that allow organisms to convert chemical energy held in molecules into energy for cellular functions. Animals eat to refuel their bodies, and their metabolism breaks down carbs, lipids, proteins, and nucleic acids to supply chemical energy for these functions. Photosynthesis is the process through which plants transform solar energy into chemical energy contained in molecules.

Energy may be divided into two categories.

Potential energy: Potential energy is energy that has been stored. The chemical energy in bonds, the electrical charge in a battery, and a penguin about to dive are all examples of this. Chemical energy is the form of potential energy that resides inside chemical bonds and is released when those connections are broken. Chemical energy is responsible for supplying energy to living cells from food. When the chemical links between food molecules are broken, energy is released.

Kinetic energy: The energy of motion is referred to as kinetic energy. The potential energy stored in chemical forms can be transformed and utilised for various life processes.

Fig: Potential Energy can be Transformed into Kinetic Energy

Energy Transformation

In cells, chemical energy is converted from one kind to another. Potential energy can be transformed into kinetic energy. The energy is required to break down (catabolic) or build up (anabolic) molecules. Cells employ specialised molecules like ATP to receive and transfer energy from one chemical process to the next. There are two types of chemical conversion that can transform energy.

1) Exergonic reaction: A chemical process that releases energy is known as an exergonic reaction
2) Endergonic reaction: A chemical reaction that absorbs energy is known as an endergonic reaction. Flow of energy

Fig: Exergonic reaction Vs. Endergonic Reaction

Flow of Energy

A steady source of energy from the outside is essential to maintain cells, tissue, organs, and organ systems. Cells absorb energy from their surroundings, either in the form of light energy or chemical energy to minimise and prevent entropy. The flow of energy begins from the sun and ultimately makes its way through the herbivore to the carnivores. Within a cell, the energy flow is consistently maintained by the consumption of fuel(food) which is metabolised. Complete or partial metabolism of nutrients produces high energy bonds containing compounds like ATP. The ATPs serve as energy currency in the living system, and they are constantly made and broken to store and use energy.

Fig: Flow of Energy in Environment

Information in The Cell

DNA is the ultimate source of information in the cell. From the beginning of life till the end, every information is stored in the small helical molecule called DNA. DNA possesses the blueprint of living organisms, and it has information about every life process. DNA is principal genetic material; hence information stored in it is referred to as genetic information. DNA possesses the information and passes it along with other organelles and molecules by a complex and highly regulated machinery. When expressed in an individual, the genetic information or genotype appears as phenotype(external appearance).

Flow of Information

The “central dogma” is a diagram that depicts the basic flow of genetic information in biological systems. According to this model, information encoded in DNA is transferred from DNA to RNA and then to proteins via translation. Mechanisms for transmitting information in various forms include reverse transcription (the production of DNA from an RNA template) and replication. This system, on the other hand, this system says nothing about how information is encoded or how regulatory signals are transferred across the numerous layers of molecule types illustrated in the model.

Fig: Central Dogma

The information held in an organism’s DNA, the sequence of nucleotides, and the assembly of its genes are referred to as genotype. Any physical trait that can be measured, such as height, weight, the quantity of ATP generated, capacity to digest lactose, sensitivity to environmental stimuli, and so on, is referred to as phenotype. Even minor differences in genotype might result in phenotypes that are sensitive to natural selection. Alleles are distinct versions of a gene found in a population of organisms that share the same gene. Different alleles can cause individual phenotypic variations and contribute to the biological diversity that is under selection pressure.

Totipotency

Totipotency is the capacity of a cell to give rise to a new organism. Plant cells have cellular totipotency, which is a significant feature. Every plant cell with a functioning nucleus and a functional membrane system is capable of producing a new plant. The totipotent cells undergo division and differentiation to produce an entire organism. These cells throughout maturation are unable to revert to their undifferentiated state, but they can do so under certain conditions like tissue damage, which is known as dedifferentiation.

Example of totipotent cells: Egg Cells and Plant cells are totipotent.  Animal cells lack totipotency, although, under certain circumstances, these cells can exhibit pluripotency under certain circumstances.

Fig: Cell Potency

Pluripotency: Pluripotent stem cells have the ability to divide into almost all cell types in an organism, but they cannot grow into a full organism on their own. Example: stem cells.

Multipotency: Multipotent stem cells can develop into a variety of cell types within a family of cells. Example: progenitor blood cells.

Factors affecting Totipotency:

1. Explant source: Organ that acts as a tissue source, physiological and ontogenic age of organ, the season of explant acquisition, size, overall, and quality of explant.
2. Constituents and nutrient media: Micronutrients are a carbon/energy supply, a nitrogen source with a decreased nitrogen content, and a plant growth regulator.
3. Cultural environment (physical form of the medium): medium pH, light quality and quantity, temperature, relative humidity, and gaseous atmosphere in vessels.

Applications of Totipotency

The totipotency has been employed in tissue culture in the following ways:

1. It aids in the rapid multiplication of desirable-character plants.
2. The reproduction of uncommon plants.
3. To break the dormancy of the seed.
4. Propagation of beneficial plants in a short amount of time.
5. Create a haploid plant
6. Create a plant that is virus-and disease-resistant.
7. Protoplast fusion and somatic hybridization are aided.

Summary

Energy is required for all living creatures to grow and reproduce, maintain their structures, and respond to their surroundings. Metabolism is a series of life-sustaining chemical processes that allow organisms to convert chemical energy held in molecules into cellular functions. Energy stored in chemical forms can be transformed and utilized for various life processes. A steady source of energy from the outside is essential to maintain cells, tissue, organs, and organ systems. The flow of energy begins from the sun and ultimately makes its way through the herbivores to the carnivores.

Complete or partial metabolism of nutrients produces high energy bonds containing compounds like ATP. The ATPs serve as energy currency in the living system, and they are constantly made and broken to store and use energy. DNA possesses the blueprint of living organisms, and it has information about every life process. The “central dogma” is a diagram that depicts the flow of genetic information in biological systems. According to this model, information encoded in DNA is transferred from DNA to RNA and then to proteins via translation. Even minor differences in genotype might result in phenotypes that are sensitive to natural selection. Totipotency is the capacity of a cell to give rise to an organism. Certain conditions such as tissue damage can cause cells to revert to their undifferentiated state. This is known as dedifferentiation.

FAQs on Flow of Energy and Information in Cell and Totipotency

Q.1. How is energy stored in a living system?
Ans: Energy can be temporarily stored in a living system in the form of a high energy phosphate bond in ATP.

Q.2. What is the first law of thermodynamics?
Ans: First law of thermodynamics: Energy can neither be created nor be destroyed.

Q.3. What is the second law of thermodynamics?
Ans: When energy is transferred, the amount of energy available at the end of the operation is less than it was at the start.

Q.4. Who proposed central dogma?
Ans: The central dogma was proposed by Francis Crick.

Q.5. Are human cells totipotent?
Ans: No! Most human cells are differentiated. Some cells like bone marrow etc., are unipotent or multipotent.

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